Adverse drug reactions

The WHO ???Roll Back Malaria Project???

Artemisinin combination therapies (ACTs) have been recommended for the treatment of malaria in countries where there is widespread resistance to commonly used antimalarial drugs. Several sub-Saharan African countries are, therefore, in the process of introducing ACTs in their malaria drug policies. However, there is limited information about the safety of ACTs outside South East Asia, where their use has been well documented. As with all other new medicinal compounds, the monitoring of a drug's safety or 'pharmacovigilance' is important, especially in areas where co-morbid conditions, such as HIV/AIDS, malnutrition and tuberculosis, are common. Because in most malaria endemic countries, particularly Africa, there are no pharmacovigilance programmes in place, it has been suggested that the introduction of ACTs offers an opportunity for these countries to put drug safety monitoring systems in place. Backed by the WHO Roll Back Malaria department and other international cooperating partners, five African countries, which are in the process of introducing ACTs (Burundi, Democratic Republic of the Congo, Mozambique, Zambia and Zanzibar), have drawn up action plans to introduce pharmacovigilance in their health sector. It is planned that once the safety monitoring of antimalarials has been established, these activities can then be extended to cover medicinal compounds used in other public health programmes, such as HIV/AIDS, tuberculosis and the immunisation programmes. This article looks at the rationale for pharmacovigilance, the process of setting up monitoring centres and the challenges of implementing the project in the region.

Investigating the Role of 2-Phenylpropenal in Felbamate-Induced Idiosyncratic Drug Reactions

Felbamate (2-phenyl-1,3-propanediol dicarbamate, FBM) can cause aplastic anemia and hepatotoxicity. The mechanism of FBM-induced toxicities is unknown; however, it has been proposed that 2-phenylpropenal, a reactive metabolite of FBM, is responsible. The pathway leading to this metabolite involves hydrolysis of FBM to 2-phenyl-1,3-propandiol monocarbamate (MCF), oxidation to 3-carbamoyl-2-phenylpropionaldehyde (CBMA), and spontaneous loss of carbon dioxide and ammonia. We made a polyclonal antibody against 2-phenylpropenal bound to protein and confirmed its specificity using ELISA. We attempted to develop an animal model of FBM-induced aplastic anemia and/or hepatotoxicity, and we also used the antibody to try to detect covalent binding of 2-phenylpropenal using immunoblotting. However, none of the animals developed evidence of bone marrow or liver toxicity, and we were unable to detect covalent binding, possibly because significantly less 2-phenylpropenal is formed in rodents than in humans. As this type of idiosyncratic drug reaction is believed to be immune-mediated, we also studied the potential of FBM and its metabolites to stimulate an immune response using the reporter antigen popliteal lymph node assay in female Balb/c mice. We found that neither FBM nor MCF induced an immune response in popliteal lymph nodes (PLNs). However, CBMA treatment appeared immunogenic, causing footpad inflammation, hardening, scab formation, and an increase in thickness. The PLN cell count in CBMA-treated mice increased 8-fold as compared to control, FBM-, or MCF-treated mice. Immunohistochemical analysis of the CBMA-exposed PLNs revealed germinal center formation, indicating B cell proliferation, later confirmed by flow cytometry. Most of the cells expressing the activation surface marker CD54 were B cells. We also found that CBMA treatment caused an increase in the production of IgM and IgG1 antibodies as well as IL-4 and IFN-gamma cytokines. Our findings indicate that 2-phenylpropenal is a very potent immunogen, supporting its possible involvement in the FBM-induced hepatotoxicity and aplastic anemia.

Improving the decision-making process in the structural modification of drug candidates: enhancing metabolic stability

The activity-exposure-toxicity relationship, which can be described as "the rule of three", presents the single most difficult challenge in the design of drug candidates and their subsequent advancement to the development stage. ADME studies are widely used in drug discovery to optimize the balance of properties necessary to convert lead candidates into drugs that are safe and effective for humans. Metabolite characterization has become one of the key drivers of the drug discovery process, helping to optimize ADME properties and increase the success rate for drugs. Various strategies can influence drug design in the decision-making process in the structural modification of drug candidates to reduce metabolic instability.

Factors that influence spontaneous reporting of adverse drug reactions: a model centralized in the medical professional

RATIONALE, AIMS AND OBJECTIVES

The spontaneous reporting of adverse drug reactions (ADRs) through the yellow card and made concrete by the knowledge and attitudes of doctors, has been rousing a great deal of bibliographical interest in recent years. However, there does not seem to be any actual revision in the theme on which the theoretical models that explain the process of decision in reporting are proposed. In this work an explanatory model of the factors that condition reporting is proposed and a revision of the literature on the subject has also been carried out.

METHODS

The proposed model is centralized in the medical professional and it considers the habit of reporting as the result of the doctor's formation and his interaction with the environment. The combination of knowledge-attitudes-practices and the theory of the satisfaction of needs seemed very adequate for ADR systematization.

RESULTS AND CONCLUSIONS

The results also indicate that, to improve the participation of health professionals in surveillance systems through spontaneous reporting, it might be necessary to design combined strategies that modify both intrinsic (knowledge, attitudes) and extrinsic (relationship between health professionals and their patients, the national health system and pharmaceutical companies) factors.

Prescription-related illness--a scandalous pandemic

Prescribed drugs are now a major cause of morbidity and mortality, particularly in the elderly. The extent of this pandemic is described and its likely causes in primary care are identified: unnecessary prescribing, imprecise diagnosis, inadequate undergraduate and postgraduate education in pharmacology and therapeutics, the uncritical application of evidence-based medicine, the outstanding development of new drugs and their sometimes unjustified promotion. Urgent action is recommended under seven headings, by health administration, epidemiologists, medical educators and prescribing doctors.

Application of data mining techniques in pharmacovigilance

AIMS

To discuss the potential use of data mining and knowledge discovery in databases for detection of adverse drug events (ADE) in pharmacovigilance.

METHODS

A literature search was conducted to identify articles, which contained details of data mining, signal generation or knowledge discovery in relation to adverse drug reactions or pharmacovigilance in medical databases.

RESULTS

ADEs are common and result in significant mortality, and despite existing systems drugs have been withdrawn due to ADEs many years after licensing. Knowledge discovery in databases (KDD) is a technique which may be used to detect potential ADEs more efficiently. KDD involves the selection of data variables and databases, data preprocessing, data mining and data interpretation and utilization. Data mining encompasses a number of statistical techniques including cluster analysis, link analysis, deviation detection and disproportionality assessment which can be utilized to determine the presence of and to assess the strength of ADE signals. Currently the only data mining methods to be used in pharmacovigilance are those of disproportionality, such as the Proportional Reporting Ratio and Information Component, which have been used to analyse the UK Yellow Card Scheme spontaneous reporting database and the WHO Uppsala Monitoring Centre database. The association of pericarditis with practolol but not with other beta-blockers, the association of captopril and other angiotensin-converting enzymes with cough, and the association of terfenadine with heart rate and rhythm disorders could be identified by mining the WHO database.

CONCLUSION

In view of the importance of ADEs and the development of massive data storage systems and powerful computer systems, the use of data mining techniques in knowledge discovery in medical databases is likely to be of increasing importance in the process of pharmacovigilance as they are likely to be able to detect signals earlier than using current methods.

Adverse Drug Reactions to Anthelmintics

BACKGROUND

Anthelmintics are commonly used in tropical areas, but are also prescribed in Western countries with other climates. However, pharmacoepidemiologic studies of these drugs are rare.

OBJECTIVE

To investigate adverse drug reactions (ADRs) due to anthelmintics.

METHODS

All spontaneous reports of ADRs associated with albendazole, diethylcarbamazine, flubendazole, ivermectin, mebendazole, niclosamide, praziquantel, pyrantel pamoate, and thiabendazole were identified in the French Pharmacovigilance Database from January 1, 1985, to August 31, 1999. For each case, the following data were recorded: age, gender, weight, ADRs, drug, dosage, and indication.

RESULTS

A total of 243 cases were found corresponding to 291 ADRs. Serious ADRs (hematologic or hepatic injury) to albendazole most often occurred when the drug was used for the treatment of echinococcosis or cysticercosis, thus requiring both high dosage and long duration of therapy. Our data show that the profile and seriousness of anthelmintic-induced ADRs vary according to their use. Furthermore, the low number of spontaneous reporting of ADRs suggests a high rate of underreporting for these drugs, which are often considered in France as orphan drugs

CONCLUSION

The improvement of reporting of serious or unrecognized (unlabeled) anthelmintic-induced ADRs will increase our knowledge of the benefit/risk ratio associated with these agents and optimize their use.

Idiosyncratic toxicity: the role of toxicophores and bioactivation

Drugs and chemicals can undergo enzyme-catalyzed bioactivation reactions within cellular systems, with the formation of reactive chemical species. These reactive metabolites can lead to thiol depletion, reversible protein modification (glutathionylation and nitration), further irreversible protein adduct formation and subsequent irreversible protein damage. The incorporation of potentially reactive chemical moieties - toxicophores - within new therapeutic agents should be limited. However, this cannot always be prevented, particularly when the structural feature responsible for toxicity is also responsible for the pharmacological efficacy. The identification and further knowledge of critical levels of thiol depletion and/or covalent modification of protein will aid in the development of new drugs. Importantly, the identification of drug-thiol conjugation should provide a warning of potential problems, yet not hinder the development of a potentially therapeutically useful drug.

Pharmacogenomic profiling in postmarketing surveillance: prospects and challenges

Adverse drug reactions (ADRs) represent a major public health and economic global problem. Growing evidence suggests that pharmacogenomics may potentially play a role in reducing drug-induced adverse events. Research efforts are increasingly directed towards this goal. However, knowledge about whether or not pharmacogenomics may be useful as a novel approach in postmarketing surveillance programs is at present rather limited. A critical analysis of some of the methodological design and ethical issues generated by the potential incorporation of pharmacogenomic profiling into pharmacosurveillance programs is presented.

Adverse drug reactions and off-label prescribing for paediatric outpatients: a one-year survey of spontaneous reports in Sweden

PURPOSE

To investigate the extent and characteristics of off-label prescribing for paediatric outpatients among drugs reported to have caused an adverse reaction.

METHODS

A retrospective, cross-sectional, observational analysis of spontaneous adverse drug reaction (ADR) reports in Sweden in the year 2000. We included all reports concerning drugs prescribed for outpatients younger than 16 years. Each ADR was classified with respect to its causality, seriousness and type of reaction. Off-label prescribing was evaluated with respect to age, dose, indication, formulation and route and frequency of administration.

RESULTS

We identified 112 patient-linked reports corresponding to 158 ADRs of which 31% were serious. Antiasthmatic drugs were most frequently suspected as a cause of almost every third adverse reaction. The average proportion of off-label drug prescribing amounted to 42.4%. It was more frequently associated with serious than non-serious ADRs and mostly due to a non-approved age or dose. The most common clinical manifestations were psychiatric disorders and mucocutaneous inflammatory reactions.

CONCLUSIONS

Off-label prescribing for paediatric outpatients is common among drugs reported to have caused an ADR. It is suggested to further identify unlabelled drugs frequently contributing to, in particular serious ADRs in children for a proper benefit-risk assessment of off-label drug use.

Reported adverse drug reactions and their determinants in Dutch children outside the hospital

PURPOSE

The interpretation of the available studies on adverse drug reactions (ADRs) in children outside the hospital is hampered because none of these studies used a control group. The aim of this study was to describe ADRs in children outside the hospital, controlled for drug use in the paediatric background population.

METHODS

Using a case-control design, we compared drugs on which a suspected ADR was reported to the Netherlands Pharmacovigilance Centre LAREB, and drugs used in the general paediatric population from the InterAction pharmacy database, both in the year 2001, for children aged 0-16 years.

RESULTS

The main findings are that ADRs were disproportionately more often reported on systemic drugs (OR 3.0; [95%CI: 1.9-4.8]), new drugs (2.4; [1.6-2.7]), anti-infective drugs (1.7; [1.1-2.7]) and nervous system drugs (2.1; [1.3-3.5]), whereas unlicensed drugs (0.1; [0.0-0.4]), frequently used drugs (0.3; [0.2-0.5]) and dermatologicals (0.1; [0.0-0.4]) were less likely to be associated with a reported ADR. Overall, the proportion of off-label prescriptions did not differ between drugs suspected of an ADR and drugs used by children in a general population.

CONCLUSIONS

The pattern of drugs associated with a reported ADR could not be solely explained on the basis of drug utilisation patterns in the general population.

Acyl glucuronide drug metabolites: toxicological and analytical implications

Although glucuronidation is generally considered a detoxification route of drug metabolism, the chemical reactivity of acyl glucuronides has been linked with the toxic properties of drugs that contain carboxylic acid moieties. It is now well documented that such metabolites can reach appreciable concentrations in blood. Furthermore, they are labile, undergo hydrolysis and pH-dependent intramolecular acyl migration to isomeric conjugates of glucuronic acid, and may react irreversibly with plasma proteins, tissue proteins, and with nucleic acids. This stable binding causes chemical alterations that are thought to contribute to drug toxicity either through changes in the functional properties of the modified molecules or through antigen formation with subsequent hypersensitivity and other immune reactions. Whereas in vitro data on the toxicity of acyl glucuronides have steadily accumulated, direct evidence for their toxicity in vivo is scarce. Acyl glucuronides display limited stability, which is dependent on pH, temperature, nature of the aglycon, and so on. Therefore, careful sample collection, handling, and storage procedures are critical to ensure generation of reliable pharmacologic and toxicologic data during clinical studies. Acyl glucuronides can be directly quantified in biologic specimens using chromatographic procedures. Their adducts with plasma or cell proteins can be determined after electrophoretic separation, followed by blotting. ELISA techniques have been used to assess the presence of antibodies against acyl glucuronide-protein adducts. This review summarizes the most recent evidence concerning biologic and toxicologic effects of acyl glucuronide metabolites of various drugs and discusses their relevance for drug monitoring. A critical evaluation of the available methodology is included.

Immunopharmacology of hypersensitivity reactions to drugs

Drug hypersensitivity reactions are characterized by their unpredictability, lack of simple dose-dependency, host sensitivity, and potentially serious clinical outcome. They occur in a small proportion of patients, and usually the predisposing factors are unknown, although there is increasing evidence for genetic predisposition and disease being significant risk factors. The current understanding of the chemical basis of immune-mediated reactions is based on the hapten hypothesis, which requires drug bioactivation, covalent binding to proteins, followed by uptake, antigen processing, and a polyclonal immune response. The recently proposed "danger hypothesis" can be considered to be an essential addition to the hapten hypothesis. According to the danger hypothesis, the immune response to a drug-derived antigen requires the presence of co-stimulatory signals and cytokines, which propagate and determine the type of immune response. The "danger signal" might result from chemical, physical, or viral stress.

The danger hypothesis--potential role in idiosyncratic drug reactions

Idiosyncratic or type B reactions are characterised by their unpredictability and lack of simple dose-dependency. They occur in a small proportion of patients, and usually the predisposing factors are unknown. A proportion of, but not all, idiosyncratic reactions are immune-mediated. Our understanding of immune-mediated reactions is based on the hapten hypothesis, which requires drug bioactivation, covalent binding to proteins, followed by uptake, antigen processing and a polyclonal immune response. The recently proposed 'danger hypothesis' can be considered to be additive to the hapten hypothesis. The hypothesis states that the immune system only responds when it detects danger. If no danger is detected, tolerance results. Thus, stimulation of an immune response to a drug-protein conjugate (signal 1) requires the presence of co-stimulatory signals and cytokines (signals 2 and 3), which propagate and determine the type of immune response. The nature of the danger signal is poorly defined, and has been proposed to include different forms of stress including chemical, physical and viral. Indeed, there are several examples where the frequency of drug hypersensitivity is increased in the presence of a viral infection, most notably in HIV disease. Nevertheless, this clinical evidence has to be regarded as being circumstantial and more direct experimental evidence is required to understand the role of 'danger' in the overall pathogenesis of drug hypersensitivity reactions.

A risky business: the detection of adverse drug reactions in clinical trials and post-marketing exercises

While it is widely acknowledged by epidemiologists, pharmacologists and physicians that adverse drug reactions (ADRs) occur with considerable frequency, within the realm of medical sociology, drug-induced risk currently receives little critical attention. This paper looks into this medical scientific 'black box' to present a comprehensive account of the epistemological and political processes at play in the detection of ADRs. By focusing on the literature generated by pharmacologists, epidemiologists and others working in the field, this paper examines the various techniques and methods used to identify and calculate ADRs both during clinical drug trials and beyond. Although risk associated with drug consumption is often presented as a scientifically calculable objective phenomenon, the attribution of causal mechanisms in determining whether the drug has caused an adverse event is a highly contingent social process, often involving complex clinical judgements. During clinical trials, variables are controlled and exclusions are imposed in order to fulfil scientific protocol requirements. These exclusionary practices mean that major patient population groups such as women and the elderly are often underrepresented during the trial process. At the time a drug product license is granted many uncertainties exist about the risk of ADRs. Once a drug is in widespread use, a more comprehensive profile of risk may begin to emerge. However, given that in everyday use drugs can interact with other drugs, alcohol and even certain foods and that drug reactions can mimic the disease they are supposed to be treating, differentiating between 'signal' and 'noise' is a messy, contingent complex process.

Genome-based pharmacogenetics and the pharmaceutical industry

Pharmacogenetic capabilities have changed markedly since The SNP Consortium made a dense single-nucleotide polymorphism (SNP) map freely available in 2001. For more than 40 years, pharmacokinetics and pharmacodynamics of drug-metabolizing molecules were the focus of practical applications. Today, it is possible to use SNP-mapping technologies to create a genetic profile of each individual that can be used to identify patterns of susceptibility genes for common diseases as well as genetic risk/efficacy factors that are related to the effects of drugs.

Adverse reactions to antidepressants in consultation-liaison psychiatry inpatients

In a practice-based, prospective study of 1,551 inpatients referred to a consultation-liaison psychiatry service and prescribed an antidepressant, an adverse drug reaction judged sufficient to warrant discontinuation of the drug was noted in 158 (10.2%). The factors associated were older age (P < 0.05); ICD-9 genitourinary disorder (mainly renal failure) (P < 0.01); DSM-IV "delirium, dementia, etc." (P < 0.05); length of stay (P < 0.001); number of visits (P < 0.001); and time spent on case (P < 0.05). Neither psychological functioning (GAF) nor physical functioning (Karnofsky ratings) were associated with a reaction, nor was multiple psychotropic drug prescription. Tricyclics were more likely than selective serotonin reuptake inhibitors/norepinephrine reuptake inhibitors to be associated with a reaction (P < 0.05). Consultation-liaison psychiatrists need to be well informed about pharmacodynamics and drug interactions in patients with physical/psychiatric comorbidity.

Ceftriaxone-induced haemolytic anaemia in a child with no immune deficiency or haematological disease

A 5-year-old girl, with no underlying immune deficiency or haematologic disease, was treated with ceftriaxone for a urinary tract infection. After receiving ceftriaxone intramuscularly, massive haemolytic anaemia developed. Laboratory studies showed the presence of an antibody against ceftriaxone, and the findings reflected immune complex type haemolysis. High-dose corticosteroids appeared to be effective therapeutically.

Safety of factor VIII inhibitor bypass activity (FEIBA): 10-year compilation of thrombotic adverse events

Published and unpublished spontaneously reported thrombotic adverse events (AEs) in factor VIII inhibitor bypass activity (FEIBA(R)) recipients were compiled for the most recent 10-year period during which FEIBA(R) units equivalent to 3.95 x 105 typical infusions were distributed worldwide. A total of 16 thrombotic AEs were documented over the 10-year period, corresponding to an incidence of 4.05 per 105 infusions (95% CI, 2.32-6.58 per 105 infusions). Disseminated intravascular coagulation (n=7) and myocardial infarction (n=5) were the most frequent thrombotic AEs. One fatality occurred in an 87-year-old metastatic cancer patient. In 13/16 (81%) patients known risk factors were present, most commonly FEIBA(R) overdose in 8/16 (50%), obesity in 3/16 (19%) and serum lipid abnormalities in 2/16 (12%). These findings indicate that thrombotic AEs in FEIBA(R) recipients are very rare. Recognition of risk factors and avoidance of FEIBA(R) overdosage may avert thrombotic AEs.

Methods and systems to detect adverse drug reactions in hospitals

Detection of adverse drug reactions (ADRs) in hospitals offers the chance to detect serious ADRs resulting in hospitalisation and ADRs occurring in hospitalised patients, i.e. patients with high comorbidity and receiving drugs that are administered only in hospitals. The most commonly applied methods involve stimulated spontaneous reporting of doctors and nurses, comprehensive collection by trained specialists and, more recently, computer-assisted approaches using routine data from hospital information systems. The different methods of ADR detection used result in different rates and types of ADRs and, consequently, in different drug classes being responsible for these ADRs. Another factor influencing the results of surveys is the interpretation of the term ADR, where some authors adhere to the strict definition of the World Health Organization and many others include intended and unintended poisoning as well as errors in prescribing and dispensing, thus referring to adverse drug events. Depending on the method used for screening of patients, a high number of possible ADRs and only few definite ADRs are found, or vice versa. These variations have to be taken into account when comparing the results of further analyses performed with these data. ADR rates and incidences in relation to the number of drugs prescribed or patients exposed have been calculated in only a few surveys and projects, and this interesting pharmacoepidemiological approach deserves further study. In addition, the pharmacoeconomic impact of ADRs, either resulting in hospitalisation or prolonging hospital stay, has been estimated using different approaches. However, a common standardised procedure for such calculations has not yet been defined. Although detection of ADRs in hospitals offers the opportunity to detect severe ADRs of newly approved drugs, these ADRs are still discovered by spontaneous reporting systems. The prospects offered by electronic hospital information systems as well as implementation of pharmacoepidemiological approaches increases the possibilities and the value of ADR detection in hospitals.

Minimizing side-effects: the clinical impact of nurse-administered 'side-effect' checklists

BACKGROUND

For those with chronic illness, the adverse effects of medication are important causes of morbidity and distress which may not always receive due attention. Guidelines and checklists may be one strategy to focus professionals' attention on long-term problems. Therefore, client-centred 'side-effect' evaluation checklists were developed to be administered and actioned by nurses.

AIM

The purpose of this study was to explore the clinical impact of these checklists on long-term users of antipsychotic medication.

METHODS

This study was undertaken with clients with enduring mental illness, in Community Mental Health Teams. In the first phase, 40 nurse-client interactions were observed. Following introduction of the evaluation checklists, 20 nurse-client interactions were observed with the checklists and 20 nurse-client interactions were observed for comparison. In addition, the views of professionals, service users and user groups on the value of the checklists were sought.

FINDINGS

Amongst the 20 clients in the intervention group, the checklists highlighted several problems, two of which were urgent. In the intervention group, the mean number of problems actioned per client increased from 0.35 (range=0-4) with no checklists to 3 (range=0-6) with the checklists. The majority (51 of 59) of actions taken to alleviate adverse effects of medication concerned physical health problems. Nurses offered appropriate advice or encouraged clients to contact the relevant agencies. No such changes were observed in the comparator group. There were no differences between groups in the number of referrals to prescribers.

IMPLICATIONS

The usefulness of the evaluation checklists for detecting unattended problems, in conjunction with the responses of service users, suggests that it may be clinically effective to establish procedures to systematically monitor people with serious mental illness for adverse drug reactions (ADRs). However, larger studies are needed to confirm this.

Management of cutaneous drug reactions

Drugs are potent chemicals that often have effects in the body beyond the desired action. These effects may range from mild and expected side effects to dramatic and life-threatening anaphylaxis. Adverse drug reactions account for between 2% and 6% of hospital admissions and may prevent administration of otherwise effective therapeutic agents. Cutaneous and mucocutaneous eruptions are the most common adverse reactions to oral or parenteral drug therapy, and the spectrum ranges from transitory exanthematous rash to the potentially fatal toxic epidermal necrolysis. Different mechanisms, including both immunologic and nonimmunologic, are responsible for cutaneous adverse drug reaction. The treatment of cutaneous drug eruptions essentially rests on accurate history, a thorough physical examination, discontinuation of the offending drug, and supportive care. The management of a cutaneous drug eruption is very much individualized, based on the clinical setting. This review aims to provide a general approach to the patient with a presumed cutaneous drug reaction.

Drug metabolism, danger signals, and drug-induced hypersensitivity

One of the most difficult challenges for the practicing allergist/immunologist today is that of evaluating and managing patients who present with histories of drug-induced reactions. Adverse drug reactions are heterogeneous, and a single drug can often cause a multitude of reactions. Because the mechanisms responsible for many of these reactions are not known, they can be, and often are, difficult to classify. Moreover, for those that have features consistent with immune-mediated mechanisms, our diagnostic tools remain limited, because little is known about the relevant immunogenic determinants of most drugs. Despite these challenges, management approaches must be devised for patients who present with histories of drug-induced disease. Simply telling such a patient to avoid all drugs that have been associated with previous adverse events leaves both the patient and the referring physician frustrated. The initial part of this review focuses on exciting current research that is furthering our understanding of the mechanisms responsible for drug-induced reactions. Because it will take time to translate this new information into clinical practice, the latter part of the review focuses on ways to evaluate and manage patients who present with drug-induced reactions using the tools and the knowledge that are currently available.

The economics of quality--a practical approach

How much time and money should we devote to quality activities? Will the results be worth the resources which we invest? How can we calculate the return on our quality investments? These questions are raised by managers, clinicians and policy-makers, but they are rarely answered, which may explain the loss of credibility of some quality activities. This paper gives examples of the cost of poor quality, describes and illustrates a simple method for quality costing, and discusses the economics of quality. It considers why there is little research and teaching about the subject, and proposes how managers and clinicians can take a more economically-informed approach to quality in public healthcare.

Genetic susceptibility to adverse drug reactions

Adverse drug reactions (ADRs) are a major clinical problem. Genetic factors can determine individual susceptibility to both dose-dependent and dose-independent ADRs. Determinants of susceptibility include kinetic factors, such as gene polymorphisms in cytochrome P450 enzymes, and dynamic factors, such as polymorphisms in drug targets. The relative importance of these factors will depend on the nature of the ADR; however, it is likely that more than one gene will be involved in most instances. In the future, whole genome single nucleotide polymorphism (SNP) profiling might allow an unbiased method of determining genetic predisposing factors for ADRs, but might be limited by the lack of adequate numbers of patient samples. The overall clinical utility of genotyping in preventing ADRs needs to be proven by the use of prospective randomized controlled clinical trials.

Safety of human albumin based on spontaneously reported serious adverse events

OBJECTIVE

To evaluate the safety of human albumin administered for therapeutic purposes.

DESIGN

Retrospective compilation of spontaneously reported serious adverse events.

SETTING

Records of serious adverse event reports received from 1990 through 1997 by nine major suppliers of therapeutic human albumin worldwide.

PATIENTS

Primarily hospitalized patients.

INTERVENTIONS

Administration of human albumin.

MEASUREMENTS AND MAIN RESULTS

The number of 40-g doses distributed by the nine suppliers during the study period was 95.4 x 10(6), corresponding to 3.82 x 10(6) kg albumin, and reported serious adverse events totaled 123. The incidence of all serious adverse events was 1.29 per 10(6) doses (95% confidence interval, 1.07 per 10(6) to 1.54 per 10(6) doses). No patient death was judged to be probably attributable to albumin administration. The incidence of fatal serious adverse events possibly related to albumin was 5.24 per 10(8) doses (95% confidence interval, 1.70 per 10(8) to 12.24 per 10(8) doses).

CONCLUSIONS

Although underreporting must be recognized as a limitation of spontaneous adverse event reports, this study encompassing approximately 100 million albumin doses provides evidence that both nonfatal and fatal serious adverse events in albumin recipients are very rare. These results provide further support for the excellent long-term safety record of human albumin.

Toxicogenetics in drug development

The major progress made in the understanding of the genetic basis of inter-individual variation in drug response, alongside the rapid advances in technology, provides major new opportunities to ensure the safe introduction of a new chemical entity into clinical practice. In essence, the aim is to get the right drug into the right patient using knowledge of factors that influence both benefit and risk. The stage of the drug development process at which genetic analysis needs to be undertaken is dependent on the frequency of the event, and the availability of clinical samples. Thus, common adverse events, or assessment of efficacy, will be feasible for testing in phases I-III. However, when a rare event is being studied, for example idiosyncratic toxicity, prospective analysis becomes impossible. Thus, retrospective studies using available drugs is important as it may provide paradigms for future drug development. Additionally, prospective collection of samples will be important so that rare adverse events identified during phase IV can then be analysed using toxicogenetic approaches. Ultimately, information obtained from toxicogenetics must be included in the Specific Product Characteristics (SPC) and thus formally translated into clinical practice in order to contraindicate the drug in specific patients with a genetically determined susceptibility to drug toxicity.

Metabolic activation in drug allergies

Drug allergies are a major problem in the clinic and during drug development. At the present time, it is not possible to predict the potential of a new chemical entity to produce an allergic reaction (hypersensitivity) in patients in preclinical development. Such adverse reactions, because of their idiosyncratic nature, only become apparent once the drug has been licensed. Our present chemical understanding of drug hypersensitivity is based on the hapten hypothesis, in which covalent binding of the drug (metabolite) plays a central role in drug immunogenicity and antigenicity. If this theory is correct, then it should be possible to develop in vitro systems to assess the potential of drugs to bind to critical proteins, either directly or indirectly after metabolic activation to protein-reactive metabolites (bioactivation) and initiate hypersensitivity. The purpose of this review is to assess critically the evidence to support the hapten mechanism, and also to consider alternative mechanisms by which drugs cause idiosyncratic toxicity.

Consultations owing to adverse drug reactions in a single practice

Data was collected over a six-month period on all patients presenting with a suspected adverse drug reaction. Analysis showed that this was a frequent reason for doctor-patient contact and that a large proportion of adverse reactions were owing to a small group of drugs.

Improving the use of pharmaceuticals through patient and community level interventions

Pharmaceuticals represent an increasing share of private and public health care expenditures. However, while most governments are interested in ensuring availability and access to drugs, the issue of adequate use of drugs remains a low priority in most third world countries. This paper summarizes the results of interventions conducted in developing countries aimed at improving patients' compliance with the advice of health professionals and/or to decrease the unnecessary use of drugs by the general population. Forty-five studies were identified through literature searches and networking; and only about a third of them fulfilled the eligibility criteria for inclusion in the review. Given the paucity of information available and the importance of the topic the authors report on all 45 studies identified. Although much remains to be explored there are several interventions that deserve to be highlighted. The authors argue that improving the use of pharmaceuticals through interventions directed only to consumers may have a small impact and suggest that in order to obtain meaningful changes it might be necessary to design interventions to modify the behavior of all the actors in the medication cycle (manufacturers, health professionals, retailers, consumers and governments). They suggest that the extraordinary therapeutic effects of antibiotics, coupled with the problems that may arise when they are inappropriately used and with the extraordinary amount of resources spent on antibiotics worldwide justify a global effort to reduce their inappropriate use and promote their adequate administration. The complexity of this type of intervention would require the support of the pharmaceutical industry, governments, private foundations, and international organizations.

Attitudes and knowledge of hospital pharmacists to adverse drug reaction reporting

AIMS

To investigate the attitudes of UK hospital pharmacists towards, and their understanding, of adverse drug reaction (ADR) reporting.

METHODS

A postal questionnaire survey of 600 randomly selected hospital pharmacists was conducted.

RESULTS

The response rate was 53.7% (n = 322). A total of 217 Yellow Cards had been submitted to the CSM/MCA by 78 (25.6%) of those responding. Half of those responding felt that ADR reporting should be compulsory and over three-quarters felt it was a professional obligation. However, almost half were unclear as to what should be reported, while the time available in clinical practice and time taken to complete forms were deemed to be major deterrents to reporting. Pharmacists were not dissuaded from reporting by the need to consult a medical colleague or by the absence of a fee. Education and training had a significant influence on pharmacists' participation in the Yellow Card Scheme.

CONCLUSIONS

Pharmacists have a reasonable knowledge and are supportive of the Yellow Card spontaneous ADR reporting scheme. However, education and training will be important in maintaining and increasing ADR reports from pharmacists.

Immunological principles of adverse drug reactions: the initiation and propagation of immune responses elicited by drug treatment

Adverse drug reactions account for between 2 to 5% of all hospital admissions and can prevent the administration of an otherwise effective therapeutic agent. Hypersensitivity or immune-mediated reactions, although less common, tend to be proportionately more serious. There is convincing evidence to implicate the immune system in the pathogenesis of hypersensitivity reactions. Our understanding of the way in which the immune system recognises drugs is based on the hapten hypothesis; the onset of hypersensitivity involves drug bioactivation, covalent binding to proteins, followed by uptake, antigen processing and T cell proliferation. Central to this hypothesis is the critical role of drug metabolism, with the balance between metabolic bioactivation and detoxification being one important component of individual susceptibility. The purpose of this review is to classify drug hypersensitivity reactions in terms of their clinical presentation, and also to consider recent advances in our understanding of the chemical, biochemical and, in particular, cellular immunological mechanisms of hypersensitivity. The following topics are reviewed: (i) drug disposition and cellular metabolism; (ii) mechanisms of antigen processing and presentation; (iii) the role of cytokines and co-stimulatory molecules in the induction and maintenance of a polarised immune response; and (iv) the application of the hapten hypothesis, danger hypothesis and serial triggering model to drug hypersensitivity. A greater understanding of the mechanism(s) of hypersensitivity may identify novel therapeutic strategies and help to combat one of the more severe forms of adverse reactions to drugs.

Clinical and economic impact of adverse drug reactions in hospitalized patients

OBJECTIVE

To identify the classes of drugs that most commonly cause adverse drug reactions (ADRs) and the characteristics of these ADRs and to determine the economic impact of ADRs on patients' length of stay and hospitalization costs.

METHODS

Data on ADRs from patients admitted to a hospital in New Jersey were collected, studied, and analyzed over a five-month period. To determine the economic impact of ADRs, patients who experienced ADRs during hospitalization were matched to controls. Each ADR was rated with regard to its severity, the patients' outcomes were determined, and specific classes of medications were identified as particularly causative of ADRs.

RESULTS

A total of 196 patients experienced ADRs; 131 of these individuals were matched with 1338 patients who did not experience an ADR, based on their diagnosis-related group code. The leading causal drugs according to therapeutic class were antiinfective (17%), cardiovascular (17%), antineoplastic (15%), and analgesics/antiinflammatory agents (15%). The organ systems most often affected were gastrointestinal (24%), dermatologic (19%), and immune systems (15%). The mean length of stay per patient differed significantly between the ADR case group and matched control group (10.6 vs. 6.8 d; p = 0.003), as did the total hospitalization cost ($22775 vs. $17292; p = 0.025).

CONCLUSIONS

Length of hospital stay and total hospitalization costs were significantly higher for patients experiencing ADRs than those who did not experience ADRs. ADR reporting systems in hospitals need to be changed and strengthened to decrease the incidence of avoidable reactions.

Advances in molecular toxicology-towards understanding idiosyncratic drug toxicity

Idiosyncratic drug toxicity is a major complication of drug therapy and drug development. Such adverse drug reactions (ADRs) include anaphylaxis, blood dyscrasias, hepatotoxicity and severe cutaneous reactions. They are usually serious and can be fatal. At present, prediction of idiosyncratic ADRs at the preclinical stage of drug development is not possible because there are no suitable animal models and we do not understand the basic mechanisms involved in the toxicity when it does occur in man. Many idiosyncratic reactions appear to have an immunological aetiology. For example, there is increasing evidence for the role of T lymphocytes in severe skin reactions. Nevertheless, the sequence of events by which a simple chemical can elicit severe tissue damage remains poorly understood and alternative novel mechanisms of toxicity must also be explored. The purpose of this article will be to review the currently accepted mechanisms of idiosyncratic drug toxicity at the chemical and the molecular levels. In particular, we will consider how recent advances in cellular immunology and molecular biology can improve our understanding of both the chemical and clinical aspects of drug hypersensitivity. Recent advances in the role of both inter- and intra-cellular signalling in the regulation of the immune response to drugs and their metabolites will be discussed. The long-term aim of such research is to provide test systems for the evaluation of drug safety and patient susceptibility to idiosyncratic drug toxicity.

Association analysis of drug metabolizing enzyme gene polymorphisms in HIV-positive patients with co-trimoxazole hypersensitivity

The use of co-trimoxazole in HIV-positive patients has been associated with a high frequency (40-80%) of hypersensitivity reactions. This has been attributed to the bioactivation of the sulphonamide component, sulphamethoxazole (SMX), to its toxic hydroxylamine and nitroso metabolites. The aim of this study was to determine whether functionally significant polymorphisms in the genes coding for enzymes involved in SMX metabolism influence susceptibility to SMX hypersensitivity. HIV-positive patients with (n = 56) and without (n = 89) SMX hypersensitivity were genotyped for allelic variants in CYP2C9, GSTM1, GSTT1, GSTP1 and NAT2 using polymerase chain reaction (PCR) and/or PCR-restriction fragment length polymorphism analysis. The CYP2C9*2/*3 genotype and CYP2C9*3 allele frequencies were nine- and 2.5-fold higher in the hypersensitive group compared to non-sensitive patients, respectively, although they were not statistically significant when corrected for multiple testing. There were no differences in the frequencies of the GSTM1 and GSTT1 null genotypes, and the slow acetylator genotype, between hypersensitive and non-sensitive patients, while GSTP1 frequency was lower (although non-significant) in the hypersensitive group [21% versus 32%, odds ratio (OR) = 0.5, Pc = 0.24]. Comparison of the genotype frequencies in HIV-positive and -negative patients showed that the NAT2 slow acetylator genotype frequency in the HIV-positive patients (74%) was significantly (Pc = 0.0003, OR = 2.3) higher than in control subjects (56%). Our results show that genetic polymorphisms in drug metabolizing enzymes are unlikely to be major predisposing factors in determining individual susceptibility to co-trimoxazole hypersensitivity in HIV-positive patients.

Clinical assessment of drug-induced disease

Physicians are often confronted with patients who state that they are "allergic" to a drug or drugs. Knowing which medications can be prescribed safely is therefore difficult, and care of such patients frustrating. The goal of this review is to help physicians develop management plans for patients who present with drug-induced diseases. It provides information that allows physicians to differentiate between reactions that are truly allergic in nature and those that are not immunologically mediated. Relevant information on medical history, physical findings, and laboratory tests that may be helpful in the assessment are discussed, and guidance is provided on when and if a drug may be safely readministered. Unfortunately, however, until we are able to better understand the mechanisms responsible for drug-induced reactions, our management tools will remain limited.

Adverse drug reactions as a cause of admission to an acute medical assessment unit: a pilot study

BACKGROUND

In this pilot study, we have investigated the frequency of adverse drug reaction (ADR)-related admissions to an acute medical assessment unit. Although ADRs are thought to be responsible for 5% of hospital admissions, there have been no recent studies in the U.K.

OBJECTIVE

To pilot such a study for estimating the incidence of ADR-related admissions to an acute medical assessment unit.

METHOD

Data were collected for 200 patients including details of concurrent illness, drug usage and reasons for admission. ADRs were assessed for causality using two previously published classification systems.

RESULTS

ADRs were responsible for admission in 15 (7.5%) patients, were present in an additional three (1.5%) patients and may have contributed to the deaths of two (1%) patients. Of the 15 ADRs suspected of causing an admission, three were considered to be 'possible' or 'unlikely', with the remaining 12 considered to be 'probable' or 'certain'. The proportion of patients identified in this study with ADR-related admissions is either similar to or larger than that found in comparable studies carried out in other hospitals. Nearly all ADRs were Type A reactions in that they were predictable and therefore potentially preventable.

CONCLUSION

This study suggests that the proportion of ADR-related admissions has not decreased in the last decade and, given the increasing numbers of acute medical admissions, the absolute numbers may have actually increased. Furthermore, the nature of drugs causing admissions has not changed substantially over the last 20 years. Strategies to reduce the burden of ADR-related admissions are urgently needed.

The rates of common adverse events reported during treatment with proton pump inhibitors used in general practice in England: cohort studies

AIMS

To estimate the rates of common adverse events in patients treated with the proton pump inhibitors omeprazole, lansoprazole and pantoprazole in general practice in England.

METHODS

In prescription-event monitoring cohort studies, data on dispensed prescriptions prescribed by general practitioners in England soon after each drug was launched were linked to subsequent clinical events recorded by the prescriber. 16 205 patients prescribed omeprazole between June 1989 and June 1990, 17 329 patients prescribed lansoprazole between May and November 1994, and 11 541 patients prescribed pantoprazole between December 1996 and June 1997 were studied.

RESULTS

The commonest adverse events in the omeprazole, lansoprazole and pantoprazole cohorts were diarrhoea (incidence: 0. 18, 0.39 and 0.23 per 1000 days of exposure, respectively); nausea/vomiting (incidence: 0.16, 0.22 and 0.18 per 1000 days of exposure, respectively); abdominal pain (incidence: 0.17, 0.21 and 0. 17 per 1000 days of exposure, respectively); and headache (incidence rates: 0.10, 0.17 and 0.15 per 1000 days of exposure, respectively). The remaining adverse events occurred at rates of less than 0.11 per 1000 days of exposure. There were little absolute differences in the rates of most events between the three proton pump inhibitors. However, diarrhoea was more commonly associated with lansoprazole compared with omeprazole (rate difference: 0.21 per 1000 days of exposure; 95% CI 0.17, 0.25; rate ratio: 2.11; 1.78, 2.51), and there was a clear age-response relationship.

CONCLUSIONS

Adverse events occurred relatively infrequently in all three cohorts. There were only small absolute differences in event rates between the three drugs, although these data suggest the hypothesis that lansoprazole is associated with more frequent occurrence of diarrhoea, particularly in the elderly.

A survey on factors that could affect adverse drug reaction reporting according to hospital pharmacists in Great Britain

INTRODUCTION

Since April 1997, UK hospital pharmacists have been invited to submit reports of suspected adverse drug reactions (ADRs) to the Committee on Safety of Medicines (CSM) and Medicines Control Agency. Three studies have investigated the involvement of hospital pharmacists in ADR reporting; however, they did not investigate the possible factors that could affect ADR reporting.

OBJECTIVES

(i) To analyse the extent to which hospital pharmacists think that specified factors could affect reporting ADRs; (ii) to identify any additional factors that could hinder reporting; and (iii) to recommend possible methods to improve reporting.

METHODS

Piloted questionnaires were sent to 548 hospital pharmacists in Great Britain randomly selected by the Royal Pharmaceutical Society of Great Britain (RPSGB) from their computer database. 346 questionnaires were returned and 280 were included in this study.

RESULTS

46% of the pharmacists had identified ADRs that were considered to be reportable according to the CSM criteria in the 6 months prior to the survey. 39% did not report these ADRs either to the CSM or the manufacturers. Only 8.2% reported that their hospitals had a written policy; conversely, 73.7% agreed that such a policy could enhance ADR reporting. Although not statistically significant, the result showed an increasing tendency to report ADRs by pharmacists who had received training. Furthermore, there was an increasing tendency to report ADRs with increasing seniority.

DISCUSSION

The results show that hospital pharmacists say they are more likely to report serious and rare ADRs and ADRs associated with newly marketed drugs. Factors that could reduce ADR reporting included being busy at work, lack of confidence in recognising ADRs and the fear of breaching patient confidentiality. Most common suggestions on methods to improve ADR reporting were to provide ADR training and meetings (34%) and a hospital written policy (24%).

RECOMMENDATIONS

ADR training and meetings would be a useful step in improving hospital pharmacist ADR reporting. Therefore, we recommend that the CSM and the RPSGB liaise with regional drug information centres and schools of pharmacy to provide more study days and training programmes for hospital pharmacists. Furthermore, the CSM should write to the 'Drugs and Therapeutics Committee' of each hospital and encourage them to develop a written local policy for pharmacist ADR reporting. Further studies should be conducted to test the recommendations noted here, assessing the response of the pharmacists in terms of absolute numbers of reports made. It would be particularly interesting to study the need for a written hospital policy and education.

Drug-related problems in hospitalised patients

Drug-related problems include medication errors (involving an error in the process of prescribing, dispensing, or administering a drug, whether there are adverse consequences or not) and adverse drug reactions (any response to a drug which is noxious and unintended, and which occurs at doses normally used in humans for prophylaxis, diagnosis or therapy of disease, or for the modification of physiological function). Furthermore, adverse drug events can be defined as an injury--whether or not causally-related to the use of a drug. Drug-related problems are relatively common in hospitalised patients and can result in patient morbidity and mortality, and increased costs. In order to get an overview of studies on drug-related problems in hospitalised patients, with specific attention to the incidence of drug-related problems and their costs, to the possibilities of prevention and to the effect of these interventions, we performed a literature search. Incidences of medication errors reported in studies vary widely. The range of reported incidences of adverse drug reactions is even wider. These wide ranges can be largely explained by the different study methods and definitions used. Problems related to drug therapy may be averted by preventive interventions. Several possibilities for prevention exist, especially for the prevention of medication errors. Prescribing, transcription and interpretation errors can be reduced by using computerised physician order entry. Together with the use of automated dispensing systems and bar-code technology, this will aid in the reduction of both dispensing and administration errors. Education of nursing staff involved in the process of drug distribution is another important measure for preventing medication errors. Finally, the introduction of systems for the early detection of adverse drug reactions may help to reduce problems related to drug therapy. Identifying risk factors that contribute to the development of adverse drug reactions, may aid in the prevention of these reactions.

Allergy to local anaesthetic: the importance of thorough investigation

A case report is presented which highlights the importance of a good history in arriving at the correct diagnosis in cases where allergy to local anaesthetic is suspected. Management of the patient is discussed and the topic of 'adverse reaction' briefly reviewed.

Epidemiology of drug exposure and adverse drug reactions in two swiss departments of internal medicine

AIMS

To explore drug exposure, frequency of adverse drug reactions (ADRs), types of ADRs, predisposing risk factors and ADR-related excess hospital stay in medical inpatients.

METHODS

Structured data regarding patient characteristics, 'events' (symptoms, laboratory results), diagnoses (ICD10) and drug therapy were collected using a computer-supported data entry system and an interface for data retrieval from electronic patient records. ADR data were collected by 'event monitoring' to minimize possible bias by the drug monitor. The causality of each event was assessed in relation to disease(s) and drug therapy.

RESULTS

The analysis included 4331 (100%) hospitalizations. The median observation period was 8 days. The median number of different drugs administered per patient and day was 6 and varied between 4 (Q1 ) and 9 (Q3 ) different drugs in 50% of all hospital days. In 41% of all hospitalizations at least one disease-unrelated event could be possibly attributed to drug therapy. Clinically relevant ADRs occurred in 11% of all hospitalizations. In 3.3% of all hospitalizations ADRs were the cause of hospital admission. The incidence of possibly ADR-related deaths was 1.4. Factors predisposing for clinically relevant ADRs were female gender and polypharmacy. ADR-related excess hospital stay accounted for 8. 6% of hospital days.

CONCLUSIONS

These data demonstrate the feasibility of the developed 'event monitoring' system for quantitative analysis of ADRs in medical inpatients. With increasing numbers of recorded patients the pharmacoepidemiological database provides a valuable tool to study specific questions regarding drug efficacy and safety in hospitalized patients.

Cytotoxicity of sulfonamide reactive metabolites: apoptosis and selective toxicity of CD8(+) cells by the hydroxylamine of sulfamethoxazole

Treatment with sulfonamide antibiotics in HIV-infected patients is associated with a high incidence (> 40%) of adverse drug events, including severe hypersensitivity reactions. Sulfonamide reactive metabolites have been implicated in the pathogenesis of these adverse reactions. Sulfamethoxazole hydroxylamine (SMX-HA) induces lymphocyte toxicity and suppression of proliferation in vitro; the mechanism(s) of these immunomodulatory effects remain unknown. We investigated the cytotoxicity of SMX-HA via apoptosis on human peripheral blood mononuclear cells and purified cell subpopulations in vitro. CD19(+), CD4(+), and CD8(+) cells were isolated from human peripheral blood by positive selection of cell surface molecules by magnetic bead separation. SMX-HA induced significant CD8(+) cell death (67 +/- 7%) at 100 microM SMX-HA, with only minimal CD4(+) cell death (8 +/- 4%). No significant subpopulation toxicity was shown when incubated with parent drug (SMX). Flow cytometry measuring phosphatidylserine externalization 24 h after treatment with 100 microM and 400 microM SMX-HA revealed 14.1 +/- 0.7% and 25. 6 +/- 4.2% annexin-positive cells, respectively, compared to 3.7 +/- 1.2% in control PBMCs treated with 400 microM SMX. Internucleosomal DNA fragmentation was observed in quiescent and stimulated PBMCs 48 h after incubation with SMX-HA. Our data show that CD8(+) cells are highly susceptible to the toxic effects of SMX-HA through enhanced cell death by apoptosis.